A sintered bearing is used with inner holes thereof being impregnated with a lubricating fluid such as a lubricating oil. As relative rotation is performed between the bearing and a shaft to be supported, the lubricating fluid with which it is impregnated oozes out to a sliding portion between the bearing and the shaft to form a lubricating film. Through the intermediation of this lubricating film, the shaft is rotatably supported. The sintered bearing has high rotational speed and is quite, it is suitably used in a portion where a particularly high bearing performance and durability are required, for example, in an automotive bearing component or a motor spindle for an information apparatus.
For example, a sintered bearing disclosed in Patent Document 1 is formed of Cu powder, SUS(Stainless steel) powder, Sn powder, and the like which are mixed at a predetermined rate. The mixed powder is compression-molded into a predetermined shape (cylindrical shape in many cases), and sintered thereafter. In this case, Sn powder having a relatively low melting point is hardened after being molten at the time of sintering, thereby functioning as a binder for coupling Cu powder and SUS powder.
[Patent Document 1] JP 2006-189081 A
[Patent Document 2] JP 11-62948 A